Method for the manufacture of broad sheets of coating material and application thereof in hydraulic engineering

ABSTRACT

A method for the manufacture of wide sheets of water impermeable coating material useful in hydraulic engineering which comprises passing carrier sheet having a width in excess of 4 meters through a molten petroleum bitumen coating composition, coating said carrier sheet on both sides with said coating composition and placing the resultant coated sheet as soon as possible onto a conveyor belt while inserting between said coated sheet and said conveyor belt a surfacing material comprising one or more paper strips and a strip of plastic film easily removed from the coated carrier sheet after cooling in a manner such that the strip of plastic film forms a lateral boundary of the surfacing material.

United States Patent [1 1 Reintjes et a1.

[ 1 Nov. 25, 1975 METHOD FOR THE MANUFACTURE OF BROAD SHEETS OF COATING MATERIAL AND APPLICATION THEREOF IN HYDRAULIC ENGINEERING [75] Inventors: Rudolf Carlo Reintjes, De Bilt;

Albert Hollander, Hoogkerk, both of Netherlands [73] Assignees: Bitumarin N.V., Zaltbommel', N. V.

Asphalt-en Chemische Fabrieken Smid 8L Hollander, Hoogkerk, both of Netherlands [22] Filed: Oct. 3, 1972 [21] Appl. No.: 294,756

[30] Foreign Application Priority Data Oct. 7, 1971 Netherlands 7113751 [52] US. Cl. 428/192; 156/278; 156/324;

[56] References Cited UNITED STATES PATENTS 1,728,471 9/1929 Bratring 117/115 X 1,939,842 12/1933 Crumb et al. 117/115 X 2,418,974 4/1947 Henry 117/115 X 2,489,985 ll/1949 Speight 117/115 X 2,517,698 7/1950 Muskat 156/247 2,665,221 l/1954 Grangraard 117/115 X 2,698,260 12/1954 Meauze et a1. 117/115 X 2,771,745 11/1956 Bramble 61/7 2,843,505 7/1958 Riedel 117/115 X 2,972,554 2/1961 Muskat et a1. 117/115 X 2,993,470 7/1961 Stickel 117/115 X 3,138,897 6/1964 McCorkle... 117/32 3,160,512 12/1964 Cash et a1... 61/7 X 3,252,822 5/1966 Burns 1 117/168 X 3,474,625 10/1969 Draper et al.... 117/168 X 3,629,041 12/1971 Shobert 156/289 3,639,202 2/1972 Simon 156/247 X 3,707,432 12/1972 Corbin..... 117/32 X 3,741,856 6/1973 Hurst 161/236 X Primary Examiner-William D. Martin Assistant Examiner-Shrive P. Beck [57] ABSTRACT A method for the manufacture of wide sheets of water impermeable coating material useful in hydraulic engineering which comprises passing carrier sheet having a width in excess of 4 meters through a molten petroleum bitumen coating composition, coating said carrier sheet on both sides with said coating composition and placing the resultant coated sheet as soon as possible onto a conveyor belt while inserting between said coated sheet and said conveyor belt a surfacing material comprising one or more paper strips and a strip of plastic film easily removed from the coated carrier sheet after cooling in a manner such that the strip of plastic film forms a lateral boundary of the surfacing material.

11 Claims, N0 Drawings METHOD FOR THE MANUFACTURE OF BROAD SHEETS OF COATING MATERIAL AND APPLICATION THEREOF IN HYDRAULIC ENGINEERING The invention relates to a method for the manufacture of broad sheets of coating material in which a carrier is passed through an impregnating composition, to broad sheets of coating material produced according to this method, and to the application thereof in hydraulic engineering.

PRIOR ART Methods for the production of coating material are already known in the roof covering industry. According to Ullmanns Encyklopadie der technischen Chemie, 3rd edition, Vol. 5, page 705 sqq., the conventional method for the production of roofing paper is a method in which a roll of paper 1 m wide is unrolled and passed through a bath of molten impregnating composition. To this end the sheet of paper first passes along a roller system comprising an upper roller conveyor and a lower roller conveyor of which. the upper roller conveyor is movable so that when a fresh sheet of paper is attached it is possible to continue impregnating by allowing the upper roller conveyor to descend. The sheet of paper is then preimpregnated and subsequently the sheet is passed through the bath of molten impregnating composition. The sheet of paper coated on both sides is passed between a number of sets of rollers in order to press the impregnating composition into the sheet of paper. The coated sheet of paper is then passed through a bath with molten coating composition (generally bitumen with filler) and subsequently brought to the desired thickness by passing the sheet between two adjustable rollers, after which the upper layer is coated with aggregate and led over a reversing roller as a result of which the aggregate-coated-layer lies underneath.

Then the still uncoated side, which now lies uppermost, is coated with aggregate. After the aggregate has been rolled in, the roofing paper is passed over a roller system comprising an upper and lower roller conveyor so that the roofing paper cools off, and then it is wound on to a reel. If bitumen is used as impregnating composition for the production of asphalt paper, use is made of a bitumen of which the softening point, established by the Ring and Ball method, is 3555C and the penetration at 25C is 200-65 dmm.

There is a growing need for liquid and/or gasimpermeable membranes for the creation of separations, among other things for the impermeabilizing of bottoms and slopes of liquid reservoirs and of dams and dikes, as well as in environmental conservation to limit the spread of undesirable substances. Because these membranes may be subject to ground movements, they must be able to withstand hyraulic excess pressures and are ballasted in order to prevent them from being forced up by excess pressures below the membrane, they should wherever necessary have a relatively large tensile strength and a relatively large elongation at break. It would indeed be possible in principle to manufacture waterimpermeable membranes according to the above-described method for the production of roof coverings, by saturating a carrier, having sufficient tensile strength and elongation at break, with an impregnating composition which guarantees water impermeability. The existing equipment for the production of roofing coverings, however, only gives sheets with a width from 1 to 2 m. Since in the application of such sheets for producing continuous membranes the sheets have to be bonded together and the bond has to be able to transfer the tensile forces without detaching, the bond, i.e. the overlap of the sheets which are joined together, must have a considerable width, e.g. 30-40 cm or more. Sheets with a width from I to 2 m are too narrow for this purpose, since in view of the overlap of at least 30 cm a great many sheets would have to be laid and the same number of bonds would have to be made in order to be able to line the bottom of a basin or the slope of a dike. Moreover, each bond is a potential source of leakage and for this reason it is desirable to minimize the number of bond seams. There is therefore a need for broad sheets of coating material with a width in excess of 2m, preferably 4 m or more.

SUMMARY OF THE INVENTION In the production of sheets of coating material with a width in excess of 2 m, difficulties are encountered if the conventional method is followed. At a width in excess of 2 m it is not possible to stretch the carrier, coated with impregnating composition or coating composition, in such a way that the freely suspended sheet does not sag in the middle and form a groove or fold. The impregnating composition or coating composition then flows to the center of the sheet so that the layer at the edges of the sheet becomes too thin. Moreover, when passing the sheet over and between the various rollers, folding can occur or the fold already formed can be pressed in. Furthermore, the various roller systems, which in that case must all have a width in excess of 2 m and preferably 4 m and more, become disproportionately expensive. The method described is therefore not suitable for the production of a carrier coated on each side with such compositions and with a width in excess of 2 m. The present invention relates to a method in which these carriers coated with such compositions can be produced in a simple manner with a width in excess of 2 m.

The invention therefore relates to a method for the preparation of broad sheets of coating material in which a carrier is passed through a molten coating composition, characterized in that the carrier, coated on both sides with coating composition, is placed as soon as possible on to a conveyor belt, on which conveyor belt cooling takes place.

Conveyor belts manufactured of material to which the coating composition does not adhere permanently are known. For example, a conveyor belt may be used of which the carrying part consists of silicone rubber, or a conveyor belt of which the carrying part is formed of laminae consisting of or coated with Teflon (polytetrafluoroethylene). However, it is more practical to use a conveyor belt manufactured of laminae of metal. These remove heat easily, and moreover, heat can be removed by air circulation in the open space between the laminae. In this case it is desirable to insert surfacing material between the carrier coated with coating composition and the conveyor belt, which surfacing material prevents the coating composition from adhering to the conveyor belt, or the laminae from penetrating into the coating composition.

The surfacing material may be, for example, a finegrained material such as sand, which is sprayed against the underside of the carrier coated with coating composition. This is difficult to realize however, because 3 the distance betwee'nthe bath with coating composition and the conveyor belt must be short and there is I therefore virtually no free space available in which this covering with fine-grained materialcan be done/It is therefore preferred to insert the surfacing material in strip form, for example by unrolling from a reel, between the carrier, which is coated with coating composition, and the conveyor belt. It is not necessary to use a single strip of surfacing material with the width of the carrier, it is also possible to use several strips of surfacing material which together cover the total width of the underside of the carrier coated with coating composition.

Suitable surfacing material are paper sheets and/or plastics film.

With a view to the subsequent bonding of the sheets of coating material, it is preferred to use two or more strips of surfacing material and the material of at least one of the strips is so chosen that it can be easily removed afterwards so as to expose a margin of coating composition to which a following sheet can be cemented or bonded. For this purpose a plastics film, e.g. a polyethylene film, is very suitable, while for the other strip (strips) of surfacing material which need not be removed afterwards may advantageously consist of paper. Accordingly, it is preferred to use as surfacing material one or more paper strips and in-addition a strip of plastics film, which forms the lateral boundary of the surfacing material. This plastics film preferably has a width of 45-70 cm; for a polyethylene film a thickness of 0.05-O.l5 mm is very suitable.

The sheet travelling with the conveyor belt is, preferably, coated with a coating material to allow for subsequent winding of the sheet on to reels.

The coating material may be used in granular form or in the form of a strip, for example a membrane, a layer of felt, a fabric or a film. Functional considerations may also be taken into account in this respect, for example because it is desired to provide anti-corrosive properties, or a protection against mechanical damage, or because it is desired to produce a certain colour effect. For subsequent use as water-impermeable membrane it is preferred to use sand as coating material.

When the above-described covering layers are used in hydraulic engineering, they are liable to be penetrated by growing plants or by plant roots as a result of which the water-impermeability is impaired, unless the carrier is proof against them. However, since it is desired to determine the choice of the carrier primarily on the basis of the desired tensile strength alone, this choice would be restricted if the carrier were also required to be proof against penetration by plants or plant roots. For that reason it is preferred to apply a separate sheet of a layer proof against plant growth, for example a plastics film.

A polyester film with a thickness of, for example, 0.025 mm is very suitable. This separate sheet may be applied internally or externally. Internal application has the advantage that this sheet cannot subsequently be easily damaged mechanically. it is therefore preferred to pass this sheet parallel to the carrier through the coating composition. if the plant-growth proof sheet is applied externally, it preferably also serves as coating material.

A rot-proof strong carrier having good adhesive properties is obtained, for example, by using therefor a fabric produced from polyamide filaments, preferably a fabric with a tensile strength of 200-300 kg/S cm of test strip width and an elongation at break of 15-25%.

The sheets of coating material preferably have a width of 4.5-5.5 m.

They can be obtained without difficulty by the method according to the invention, while suitable carriers with a correponding width can be supplied by the industry in large lengths.

The method according to the invention may be used for impregnating and coating of carriers with compositions of varying type, e.g. montan wax, rosin, petroleum bitumen and coal tar. For hydraulic engineering applications petroleum bitumen is very suitable. It is permanently water-impermeable and proof against water of varying quality and is available in large quantities in any desired specification. In connection with the processing temperature, the water temperature and the load on the finished water-impermeable membrane, it is preferred to choose a blown bitumen with a Ringand-Ball softening point of -l 10C and a penetration of lO-60 dmm at 25C. For application of ballasted membranes in a temperate climate, a very suitable composition is one consisting of /45 bitumen (this is a blown bitumen with a softening point between 70C and C and a penetration between 40 and 50 dmm).

The coating composition must meet varying requirements. In addition to adequate fluidity in the molten state at not excessively high temperature, the composition must be sufficiently flexible in the cooled state and display the minimum of flow. Petroleum bitumen, and in particular blown petroleum bitumen, meets these requirements in general, but if desired the rheological properties may be improved by the addition of a suitable component, for example a filler, an elastomer or a fibrous material. It is preferred to use asbestos fibre, which is suitably used in quantities of 3-8% by weight, based on the finished mixture. For use in a temperate climate, a mixture of 75/45 bitumen and 3-8% by weight of asbestos fibre, in particlar 45-55% by weight, is very suitable.

On leaving the bath, the carrying layer, covered with coating composition, is preferably first passed through a slit of which the width may be adjusted to the desired thickness of the coating material to be produced (e.g. l-20 mm), whereby the excess coating composition is scraped off and a smooth surface is obtained.

EXAMPLE A sheet of nylon with a width of 5 m and a tensile strength of 250 kg/S cm of trial strip width was passed through a composition consisting of a mixture of by weight of 75/45 bitumen and 5% by weight of shortfibred asbestos. This mixture had a temperature of C. At the same time three partly overlapping sheets of polyester film with a total width of 5 m and a thickness of 0.023 mm were passed through the bath and joined to the sheet of nylon fabric. These sheets were passed through the bath at a rate of 4 m/min. The combination of nylon fabric, polyester film and bitumen compound was passed out of the composition through a slit with a width of 5 mm. The resultant sheet was then placed on a 5.5 m wide conveyor belt, while between the resultant sheet and the conveyor belt three N partly overlapping strips of surfacing material were passed having a total width of 5 m, viz. two strips of 60 g kraft paper with a width of 2.50 m and a strip of 0.1 mm thick polyethylene film 65 cm in width, the strip of polyethylene film forming a marginal strip of the surfacing layer. The conveyor belt was built up of vertically standing, crenellate laminae which lie transverse to the direction of travel and are movable with respect to each other. The carrying part of the conveyor belt was 40 m in length. At a distance of 3 m measured from the slit, sand was sprinkled on the upper side of the sheet, travelling at a speed of 4 m/min. Halfway along the conveyor belt cooling air was blown over the sheet by means of two blowers arranged on either side of the conveyor belt. The cooled sheet was cut into 29 meter pieces and each piece was wound on to a reel and transported to the work.

The work consisted of the application of a waterimpermeable lining to two excavated drinking water basins of which one had a depth of 21.5 m and a surface area of 105 hectares and the other a surface area of 219 hectares and a maximum depth of 23.5 in, against the penetration of ground water by means of laying a water-impermeable membrane on the slope of the dike and ballasting the membrane in order to prevent it from being forced up in the event of excess pressure of the ground water. This work was executed as follows. A reel of the obtained covering material was unrolled on the slope of the dike with the sand coated side towards the slope. Then the polyethylene film was removed and a second reel was unrolled in a similar manner with the strip of polyethylene film turned away from the sheet laid first, in such a way that the exposed bituminous layer of the first-laid sheet was just covered by the second sheet. Next the second sheet was bonded to the bit'uminous layer of the first layer be means of molten 75/45 bitumen. This procedure was repeated for each subsequent sheet. In this way the entire annular dike around the basin was provided over a slope length of 29 m with a water-impermeable membrane on the slope facing the basin. The membrane was then ballasted with sand.

We claim:

1. A method for the manufacture of wide sheets of water impermeable coating material useful in hydraulic engineering which comprises passing carrier sheet having a width in excess of 4 meters through a molten petroleum bitumen coating composition, coating said carrier sheet on both sides with said coating composition,

placing the resultant coated sheet as soon as possible onto a conveyor belt while inserting between said coated sheet and said conveyor belt a surfacing material comprising one or more paper strips and a strip of plastic film easily removed from the coated carrier sheet after cooling in a manner such that the strip of plastic film forms a lateral boundary of the surfacing material, and cooling said coated sheet,

thereby preventing said sheet from sagging toward the center to allow said molten coating composition to flow toward the center of the sheet so that 6 the layer of coating composition at the edge of the sheet becomes too thin, and preventing said sheet from folding, while providing a sheet with an exposable margin of coating composition for bond- 2. A method, as in claim 1, where the upper side of the sheet of coating material is provided with a coating material, while on the conveyor belt.

3. A method, as in claim 2, where the coating material consists of sand.

4. A method, as in claim 1, where the carrier and a plastic film which is proof against plant growth are passed through the molten coating composition.

5. A method, as in claim 1, where the carrier has a width of 4.5 to 5.5 meters.

6. A method, as in claim 1, where the carrier consists of a polyamide fabric.

7. A method, as in claim 1, where the petroleum bitumen is blown petroleum bitumen with a ring and ball softening point of 1 10C. and a penetration of 10-60 dmm at 25C.

8. A method, as in claim 1, where the coating composition is blown bitumen to which asbestos fiber had been added in a quantity of 38% by weight based on the mixture.

9. A sheet of covering material obtained by means of the method of claim 1.

10. A method for the manufacture of wide sheets of water impermeable coating material useful in hydraulic engineering which comprises passing a nylon fabric carrier sheet having a width of 4.5 to 5.5 meters, a tensile strength of 200-300 Kg per 5 cm test strip with an elongation at break of 15-25%, and one or more sheets of polyester film with a thickness of 0.01 to 0.03 mm, through a coating composition bath containing molten /45 bitumen having suspended therein 5% by weight of asbestos fiber, coating said sheets with the coating composition,

withdrawing the sheet coated with bitumen composition from the bath through a slit-shaped opening with a width of 1-20 mm, scraping off excess bitumen, placing the resultant coated sheet as soon as possible onto a conveyor belt while inserting between said coated sheet and said conveyor belt a surfacing material comprising one or more paper strips and at an edge a 45-70 cm wide strip of polyethylene film with a thickness of 0.05-0.15 in a manner that the polyethylene strip forms the lateral boundary of the surfacing matter, said strips of surfacing material preventing the coated sheet from adhering to the conveyor belt, and

sprinkling the upward facing surface of tue bitumen mixture with sand.

11. A sheet of covering material obtained by means of the method of claim 10. 

1. A METHOD FOR THE MANUFACTURE OF WIDE SHEETS OF WATER IMPERMEABLE COATING MATERIAL USEFUL IN HYDRAULIC ENGINEERING WHICH COMPRISES PASSING CARRIER SHEET HAVING A WIDTH IN EXCESS OF 4 METERS THROUGH A MOLTEN PETROLEUM BITUMEN COATING COMPOSITION, COATING SAID CARRIER SHEET ON BOTH SIDES WITH SAID COATING COMPOSITION, PLACING THE RESULTANT COATED SHEET AS SOON AS POSSIBLE ONTO A COVEYOR BELT WHILE INSERTING BETWEEN SAID COATED SHEET AND SAID CONVEYOR BELT A SURFACING MATERIAL COMPRISING ONE OR MORE PAPER STRIPS OF PLASTIC FILM EASILY REMOVED FROM THE COATED CARRIER SHEET AFTER COOLING IN A MANNER SUCH THAT THE STRIP OF PLASTIC FILM FORMS A LATERAL BOUNDARY OF THE SURFACING MATERIAL, AND COOLING SAID COATED SHEET, THEREBY PREVENTING SAID SHEET FROM SAGGING TOWARD AND CENTER TO ALLOW SAID MOLTEN COATING COMPOSITION TO FLOW TOWARD THE CENTER OF THE SHEET THAT THE LAYER OF COATING COMPOSITION AT THE EDGE OF THE SHEET BECOMES TOO THIN, AND PREVENTING SAID SHEET FROM FOLDING, WHILE PROVIDING A SHEET WITH AN EXPOSABLE MARGIN OF COATING COMPOSITION FOR BONDING.
 2. A method, as in claim 1, where the upper side of the sheet of coating material is provided with a coating material, while on the conveyor belt.
 3. A method, as in claim 2, where the coating material consists of sand.
 4. A method, as in claim 1, where the carrier and a plastic film which is proof against plant growth are passed through the molten coating composition.
 5. A method, as in claim 1, where the carrier has a width of 4.5 to 5.5 meters.
 6. A method, as in claim 1, where the carrier consists of a polyamide fabric.
 7. A method, as in claim 1, where the petroleum bitumen is blown petroleum bitumen with a ring and ball softening point of 70*-110*C. and a penetration of 10-60 dmm at 25*C.
 8. A method, as in claim 1, where the coating composition is blown bitumen to which asbestos fiber had been added in a quantity of 3-8% by weight based on the mixture.
 9. A sheet of covering material obtained by means of the method of claim
 1. 10. A method for the manufacture of wide sheets of water impermeable coating material useful in hydraulic engineering which comprises passing a nylon fabric carrier sheet having a width of 4.5 to 5.5 meters, a tensile strength of 200-300 Kg per 5 cm test strip with an elongation at break of 15-25%, and one or more sheets of polyester film with a thickness of 0.01 to 0.03 mm, through a coating composition bath containing molten 75/45 bitumen having suspended therein 5% by weight of asbestos fiber, coating said sheets with the coating composition, withdrawing the sheet coated with bitumen composition from the bath through a slit-shaped opening with a width of 1-20 mm, scraping off excess bitumen, placing the resultant coated sheet as soon as possible onto a conveyor belt while inserting between said coated sheet and said conveyor belt a surfacing material comprising one or more paper strips and at an edge a 45-70 cm wide strip of polyethylene film with a thickness of 0.05-0.15 in a manner that the polyethylene strip forms the lateral boundary of the surfacing matter, said strips of surfacing material preventing the coated sheet from adhering to the conveyor belt, and sprinkling the upward facing surface of tue bitumen mixture with sand.
 11. A sheet of covering material obtained by means of the method of claim
 10. 